1. Field of the Invention
This invention relates to a modular stairway system and more particularly relates to a reversible sectional stairway system which can be easily assembled and installed on circular structures of different diameters or on other structures having non-linear walls.
2. Description of the Prior Art
It has heretofore been considered impractical, if not impossible, to prefabricate stairways for circular structures because of the large range of diameters and therefore different radii of curvature. In addition, previous attempts to prefabricate individual components have usually required custom installation on the structure. This custom installation has usually involved welding of the individual components, both together and to the structure. Such stairways also demonstrated the disadvantage of being principally supported by the welds on the wall of the structure. Furthermore, the significant amount of labor involved in installing the stairway is expensive and time consuming.
In another type of prior art construction, there is provided a stairway which is attached to the top of the structure and which slopes downwardly away from the tank and is anchored to the ground at a substantial distance from the structure. This construction is cumbersome and occupies an excessive amount of ground space.
Other previous stairway constructions have consisted of a first stringer, either attached to or spaced from the structure wall, which conformed to the curvature thereof, with a second stringer corresponding in shape and curvature to the first stringer horizontally spaced therefrom. Between the stringers is interposed a plurality of stairs forming the steps of the stairway. The disadvantage of this type of stairway is that since the stringers conform to the curvature of the circular structure they must be either custom built or prefabricated for circular structures of fixed diameter. Therefore, it would be a decided improvement over the prior art to have a stairway system which utilized modular component sections, which could be prefabricated to fit circular structures of varying diameters, and which could be conveniently and inexpensively assembled and installed on the structure.
Accordingly, a primary object of this invention is to provide a practical stairway system which utilizes prefabricated straight modular component sections which can be installed on circular structures of different diameter and therefore different radii of curvature in either a clockwise or counter-clockwise direction.
Another object is to provide a stairway system which can be easily and inexpensively manufactured, shipped disassembled and easily assembled and installed on a circular structure or other structure having curved or non-linear walls, with a minimum of labor and without the necessity of welding.
A further object is to provide a stairway system in which individual components can be conveniently and economically replaced due to the sectional construction and bolted installation.
A still further object is to provide a stairway system in which the sectional components have dimensions and corresponding hole punchings that match the bolt spacings on standardized circular structures such as grain storage bins.
A related object is to provide a stairway system which is safer to climb than the ladder systems which are frequently utilized due to the lack of inexpensive prefabricated stairway systems.